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Balsam Wooly Adelgid

Adelges piceae

The Balsam wooly agelid is very small, and has a covering of white wax-like threads. This agelid affects true firs in California and other western states.

Location: California, Oregon, Washington, Idaho, and British Columbia, BWA

Impact Significance: Damage Occurances

Hosts: Balsam woolly adelgid feeds predominantly on subalpine fir and grand fir.

Biology:  This adelgid is very small, 1mm or less in length, and relatively inconspicuous except for a covering of white wax-like threads that gives the insect its name. Two unique features of this adelgid: all are female, capable of starting a new infestation alone, and all are flightless.

Damage:  Heavy balsam woolly adelgid feeding modifies the bark and after a few years they can’t penetrate the thicker layers. Attractive feeding space on the tree diminishes and populations die out. If a tree survives the initial infestaton, mortality will likely be avoided.

Balsam Woody Adelgid
Balsam Woody Adelgid

Balsam Woody Adelgid

Balsam Woody Adelgid
Balsam Woody Adelgid

Balsam Woody Adelgid

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Eastern

Cooley Spruce Gall Adelgid

Adelges cooleyi

More information coming soon

Cooley spruce gall adelgid, William M. Ciesla, Forest Health Management International, Bugwood.org
Cooley spruce gall adelgid, William M. Ciesla, Forest Health Management International, Bugwood.org

Cooley spruce gall adelgid

Cooley spruce gall adelgid, Whitney Cranshaw, Colorado State University, Bugwood.org
Cooley spruce gall adelgid, Whitney Cranshaw, Colorado State University, Bugwood.org

Cooley spruce gall adelgid

Cooley spruce gall adelgid, William M. Ciesla, Forest Health Management International, Bugwood.org
Cooley spruce gall adelgid, William M. Ciesla, Forest Health Management International, Bugwood.org

Cooley spruce gall adelgid

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Gouty Pitch Midge

Cecidomyia piniiopsis

More information coming soon

Gouty pitch midge, Donald Owen, California Department of Forestry and Fire Protection, Bugwood.org
Gouty pitch midge, Donald Owen, California Department of Forestry and Fire Protection, Bugwood.org

Gouty pitch midge

Gouty pitch midge cocoon, Donald Owen, California Department of Forestry and Fire Protection, Bugwoo
Gouty pitch midge cocoon, Donald Owen, California Department of Forestry and Fire Protection, Bugwoo

Gouty pitch midge cocoon

Gouty pitch midge, Donald Owen, California Department of Forestry and Fire Protection, Bugwood.org
Gouty pitch midge, Donald Owen, California Department of Forestry and Fire Protection, Bugwood.org

Gouty pitch midge

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Hemlock Woolly Adelgid

Adelges tsugae

Hemlock woolly adelgid (HWA), Adelges tsugae, is member of the Sternorrhyncha suborder of the Order Hemiptera. It feeds by sucking sap from hemlock and spruce trees.

Location: Oregon, California, Virginia, Delaware, Maryland, New York, Pennsylvania, New Jersey, Connecticut, Rhode Island, West Virginia, North Carolina, South Carolina, Georgia, Maine, Vermont, New Hampshire, Tennessee, and Kentucky

Impact Significance: Generally, this pest has not caused severe damage in the western United States. However, in much of Pennsylvania it has caused significant damage to eastern hemlock, Tsuga canadensis in ornamental plantings and the forest.

Hosts: Hemlock and spruce trees.

Biology: The hemlock woolly adelgid (HWA, Adelges tsugae) is an aphid-like, invasive insect.

Damage:  Moderate hemlock woolly adelgid populations may cause a reduction in tree health. Severe infestations may result in premature needle drop, reduced twig growth, dieback, or death of trees.

Hemlock woody adelgid, Michael Montgomery, USDA Forest Service, Bugwood.org
Hemlock woody adelgid, Michael Montgomery, USDA Forest Service, Bugwood.org

Hemlock woody adelgid

Hemlock woody adelgid, John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwoo
Hemlock woody adelgid, John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwoo

Hemlock woody adelgid

Hemlock woody adelgid, Michael Montgomery, USDA Forest Service, Bugwood.org
Hemlock woody adelgid, Michael Montgomery, USDA Forest Service, Bugwood.org

Hemlock woody adelgid

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Pine Wood Nematode

Bursaphelenchus xylophilus

Status:  Uncertain, however thought to be native throughout North America

 

Hosts (in California):  Found in trees or logs of over 30 conifer species including Abies (fir), Pinus (pines), Cedrus (cedars), Larix (larch), Picea (spruce) and Pseudotsuga (Douglas-fir).  Most trees are resistant except when seriously water stressed.  Primarily exists as a problem in landscape plantings.  Main landscape trees impacted are exotic pines including Japanese black (P. thunbergii), Japanese red (P. densiflora), Scots (P. sylvestris) and Austrian (P. nigra) pines.

 

Management: No major management options exist for pine wood nematode.  Individually infected branches can be trimmed.  Infected landscape trees can be replaced with non-hosts or native species.

 

Highlights:  Nematodes are microscopic eel-like organisms.  The pine wood nematode lives within the cells of its host plants or within its insect vector.  Insects, primarily longhorn beetles in the genus Monochamus (wood boring long horn beetles), vector the nematodes when they attack dead or dying trees or when feeding or laying eggs on new hosts.  Within the tree the nematodes move first to the resin ducts and then to xylem cells.  Toxins produce cause the cells to break down, fill with air and become unable to conduct fluid resulting in a wilting of living trees.  The pest is also known to spread blue stain fungi into healthy trees. The nematodes reproduce rapidly (the lifecycle can be completed in as little as four days when conditions are best).  Damage to healthy living trees is rare in California and occurs primarily on non-native pines in landscaping settings.  However, the nematodes have become a major pest causing extensive damage when introduced to Japan and other parts of East Asia.

Recommended Literature

Bergdahl, D.R. 1988. Impact of pine wood nematode in North America: present and future. Journal of Nematology. 20(2):260-265. 

Dwinnell, L.D. 1993. Incidence of the pine wood nematode in green coniferous sawn wood in Oregon and California. USDA Forest Service Research Note SE-367. 4pp.

Dwinnell, L.D. 1997. The pine wood nematode: regulation and mitigation. Annu. Rev. Phytopathol. 35:153-166

Pine Wood Nematode Adult. Photo by J. Eisenback
Pine Wood Nematode Adult. Photo by J. Eisenback

Pine Wood Nematode Adult.

White spotted pine sawyer (a vector of the nematode).  Photo by E. Nelson
White spotted pine sawyer (a vector of the nematode). Photo by E. Nelson

White spotted pine sawyer (a vector of the nematode).

Wilting of Scots Pine in Northeastern US. Photo by USDA Forest Service
Wilting of Scots Pine in Northeastern US. Photo by USDA Forest Service

Wilting of Scots Pine in Northeastern US.

Pine Wood Nematode Adult. Photo by J. Eisenback
Pine Wood Nematode Adult. Photo by J. Eisenback

Pine Wood Nematode Adult.

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Sequoia Pitch Moth

Synanthedon sequoia

More information coming soon

Sequoia pitch moth, Christine Buhl, Oregon Department of Forestry, Bugwood.org
Sequoia pitch moth, Christine Buhl, Oregon Department of Forestry, Bugwood.org

Sequoia pitch moth

Sequoia pitch moth larva. Christine Buhl, Oregon Department of Forestry, Bugwood.org
Sequoia pitch moth larva. Christine Buhl, Oregon Department of Forestry, Bugwood.org

Sequoia pitch moth larva

Sequoia pitch moth, Christine Buhl, Oregon Department of Forestry, Bugwood.org
Sequoia pitch moth, Christine Buhl, Oregon Department of Forestry, Bugwood.org

Sequoia pitch moth

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Wood Wasps

Siricidae

More information coming soon